It's worth noting that Zubr decided that during the Night of the Living Dead, the Baron would be able to use the Double Deal, but he didn't write this anywhere specifically, and Pobeditel picked up on his idea and responded to it. Perhaps the mafia really initially thought that their Double Deal would only work when the Night of the Living Dead comes out during the day. At first, I thought they were a priest and an ink in cahoots, who decided that the mafia had such a Double Deal, but now that it's clear that Pobeditel is mafia, it's worth considering Zubr as a candidate.
2) If I were mafia, what would be the point of paying attention to this subtlety? It's very easy to go into the Night of the Living Dead.
3) Koshka executed Pobeditel based on my tip, if you remember. And he turned out to be the Baron. A big sacrifice to clear someone, even though neither Double Deal was used.
I'm just assuming that you're guilty of Amko's death (the clue deduction from Nebo is very good - and he's at most a maniac).

Барон "Vampires"
Отдай свои прошлые сны,
В сомненьях себя обрети,
В бешеном танце душа кружится!
Не думай, что будет потом,
Здесь и сейчас мы живем,
Стань хоть на миг сам собой, слышишь!